A conventional switch gear disclosed in U.S. Pat. No. 6,244,984 contains a housing 2, and the housing 2 has a rotatable driving gear 6 for driving a drive shaft 5, a sun gear 9, and a clutch gear 10, wherein a coaxially hollow gear 13 and an inner gear 14 mesh with at least one planetary gear 12 and two cam discs 15, wherein a number of inner teeth 16 of each cam disc 1 is larger than a number of teeth of the inner gear 14, and the each cam disc 15 has two controlling cams 17 for touching an electrical switch. However, such a conventional switch gear cannot be adjusted at a larger velocity ratio and has complicated structure.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.